I am for CFL's, but with caution. Here are some typical Lumen numbers (Inc-Incandescent).
40W-Inc @ 450
9W-CFL @ 500
60W-Inc @ 800
13W-CFL @ 775
75W-Inc @ 1000
18W-CFL @ 1075
100W-Inc @ 1500
26W-CFL @ 1500
32W-CFL @ 2000
These will all vary depending on the manufacturer, the lamp (and ballast combination), the ambient temperature, and other factors.
My caution is there seem to be some real poor CFL lamps available (both in percieved light and short ballast life). I wish that I knew which ones (my experience was with TCP which were the biggest waste of money I have ever done in lighting). Look for a minimum CRI (Color Renditioning Index) of 82. You will likely have to go to the manufacturers literature.
Some express the opinion that an incandescent fixture is not listed for using CFL's and thus CFL's are not allowed. CFL's of the proper listed styles for the fixture, and not exceeding the fixtures wattage are allowed.
Shane
